package com.test.utils;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 微信验证工具类
 * 
 * @author 殷田
 *
 */
public class WeiXinSignatureUtil
{
	// 与接口配置信息中的Token要一致
	private static String token = "weixin_123";

	/**
	 * 验证签名
	 * 
	 * @param signature
	 * @param timestamp
	 * @param nonce
	 * @return
	 */
	public static boolean checkSignature( String signature, String timestamp, String nonce )
	{
		String[] arr = new String[] { token, timestamp, nonce };
		// 将token、timestamp、nonce三个参数进行字典序排序
		// Arrays.sort(arr);
		sort( arr );
		StringBuilder content = new StringBuilder();
		for ( int i = 0; i < arr.length; i++ )
		{
			content.append( arr[i] );
		}
		MessageDigest md = null;
		String tmpStr = null;

		try
		{
			md = MessageDigest.getInstance( "SHA-1" );
			// 将三个参数字符串拼接成一个字符串进行sha1加密
			byte[] digest = md.digest( content.toString().getBytes() );
			tmpStr = byteToHexStr( digest );
		}
		catch ( NoSuchAlgorithmException e )
		{
			e.printStackTrace();
		}
		content = null;
		// 将sha1加密后的字符串可与signature对比，标识该请求来源于微信
		return tmpStr != null ? tmpStr.equals( signature.toUpperCase() ) : false;
	}

	/**
	 * 将字节数组转换为十六进制字符串
	 * 
	 * @param byteArray
	 * @return
	 */
	private static String byteToHexStr( byte[] byteArray )
	{
		String strDigest = "";
		for ( int i = 0; i < byteArray.length; i++ )
		{
			strDigest += byteToHexStr( byteArray[i] );
		}
		return strDigest;
	}

	/**
	 * 将字节转换为十六进制字符串
	 * 
	 * @param mByte
	 * @return
	 */
	private static String byteToHexStr( byte mByte )
	{
		char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
						'F' };
		char[] tempArr = new char[ 2 ];
		tempArr[0] = Digit[( mByte >>> 4 ) & 0X0F];
		tempArr[1] = Digit[mByte & 0X0F];
		String s = new String( tempArr );
		return s;
	}

	public static void sort( String a[] )
	{
		for ( int i = 0; i < a.length - 1; i++ )
		{
			for ( int j = i + 1; j < a.length; j++ )
			{
				if ( a[j].compareTo( a[i] ) < 0 )
				{
					String temp = a[i];
					a[i] = a[j];
					a[j] = temp;
				}
			}
		}
	}
}